$B_{1} = \# \left\{\left\{\left\{1\right\}\right\}\right\} = 1$

Definitions:

Fungrim symbol | Notation | Short description |
---|---|---|

BellNumber | $B_{n}$ | Bell number |

Cardinality | $\# S$ | Set cardinality |

Source code for this entry:

Entry(ID("534f7d"), Equal(BellNumber(1), Cardinality(Set(Set(Set(1)))), 1))